Effect of red osier dogwood extract on in vitro gas production, dry matter digestibility, and fermentation characteristics of forage-based diet or grain-based diet.

This in vitro batch culture study investigated the effects of red osier dogwood (ROD) extract supplementation on gas production (GP), dry matter disappearance (DMD), and fermentation characteristics in high forage (HF) and high grain (HG) diets with varying media pH level. The experiment was a factorial arrangement of treatments in a completely randomized design with 2 media pH (5.8 and 6.5) × 4 dose rates of ROD extract (0, 1, 3, and 5% of DM substrate). An additional treatment of monensin was added as a positive control for each pH level. The HF substrate consisted of 400 and 600 g/kg DM barley-based concentrate and barley silage, respectively, while the HG substrate contained 100 and 900 g/kg DM barley silage and barley-based concentrate, respectively. Treatments were incubated for 24 h with GP, DMD and fermentation parameters determined. No interaction was detected between the media pH level and ROD extract dose rate on GP, DMD and most of the fermentation parameters. The GP, DMD, and total volatile fatty acid (VFA) concentration were greater (P = 0.01) with media pH of 6.5 in both HF and HG diets. The GP were not affected by increasing ROD dose rate, except that GP linearly decreased in the HF (P = 0.04) and HG (P = 0.01) diets at 24 h; the DMD tended to linearly decrease at pH 6.5 (P = 0.06) for both HF and HG diets and at pH 5.8 (P = 0.02) for the HG diet. Adding ROD extract to the HF and HG diets linearly (P = 0.01) increased the acetate molar proportion at high or low media pH and consequently, the acetate to propionate (A:P) ratio linearly (P ≤ 0.04) increased. Supplementation of ROD extract to the HF diet linearly (P = 0.04) decreased the molar proportion of propionate at pH 6.5 (interaction between pH and ROD extract; P = 0.05), but had no effect on propionate proportion when added to the HG diet. Moreover, the proportion of branched-chain fatty acids linearly (P = 0.03) decreased with ROD extract supplementation at low pH (interaction, P < 0.05) for HF diet and linearly decreased (P = 0.05) at pH 6.5 for HG diet (interaction, P < 0.05). The NH3-N concentration was not affected by ROD supplementation in the HF diet but it linearly (P = 0.01) decreased with increasing dose rate in the HG diet. Methane concentration tended to linearly (P = 0.06) increase with ROD extract supplementation at high pH for HF diet and linearly increased at pH 5.8 (P = 0.06) and pH 6.5 (P = 0.02) for HG diet. These results indicate that the decreased DMD and increased A:P ratio observed with addition of ROD extract may be beneficial to HG-fed cattle to reduce the risk of rumen acidosis without negatively impacting fiber digestion.

Nutritional impact of excluding red meat from the Canadian diet.

The objective of the study was to examine differences in nutrient intake between consumers and non-consumers of red meat and to assess nutritional adequacy of consumers relative to Recommended Daily Allowance (RDA) in Canada. Matching estimators were used to identify differences in nutrient intake between the two groups. Statistically significant differences were observed in nutrient intake between red meat consumers and non-consumers, including lower daily intake of protein, riboflavin, niacin, vitamin D, and zinc and a higher daily intake of dietary fiber, folate, and magnesium among Canadians who did not consume red meat. Further, red meat consumers and non-consumers had nutrient intakes below RDA for dietary energy, fiber, and calcium. While individuals who did not consume red meat were at increased risk of calcium, vitamin D, energy, and potassium inadequacy, those who consumed red meat were at increased risk of dietary fiber, vitamin A, and magnesium inadequacy.

BOARD-INVITED REVIEW: Quantifying water use in ruminant production.

The depletion of water resources, in terms of both quantity and quality, has become a major concern both locally and globally. Ruminants, in particular, are under increased public scrutiny due to their relatively high water use per unit of meat or milk produced. Estimating the water footprint of livestock production is a relatively new field of research for which methods are still evolving. This review describes the approaches used to quantify water use in ruminant production systems as well as the methodological and conceptual issues associated with each approach. Water use estimates for the main products from ruminant production systems are also presented, along with possible management strategies to reduce water use. In the past, quantifying water withdrawal in ruminant production focused on the water demand for drinking or operational purposes. Recently, the recognition of water as a scarce resource has led to the development of several methodologies including water footprint assessment, life cycle assessment, and livestock water productivity to assess water use and its environmental impacts. These methods differ with respect to their target outcome (efficiency or environmental impacts), geographic focus (local or global), description of water sources (green, blue, and gray), handling of water quality concerns, the interpretation of environmental impacts, and the metric by which results are communicated (volumetric units or impact equivalents). Ruminant production is a complex activity where animals are often reared at different sites using a range of resources over their lifetime. Additional water use occurs during slaughter, product processing, and packaging. Estimating water use at the various stages of meat and milk production and communicating those estimates will help producers and other stakeholders identify hotspots and implement strategies to improve water use efficiency. Improvements in ruminant productivity (i.e., BW and milk production) and reproductive efficiency can also reduce the water footprint per unit product. However, given that feed production makes up the majority of water use by ruminants, research and development efforts should focus on this area. More research and clarity are needed to examine the validity of assumptions and possible trade-offs between ruminants' water use and other sustainability indicators.

Effects of Propionibacterium strains on ruminal fermentation, nutrient digestibility and methane emissions in beef cattle fed a corn grain finishing diet.

Twenty ruminally cannulated beef heifers were fed a high corn grain diet in a randomized block design to determine the effect of three direct fed microbial (DFM) strains of Propionibacterium on ruminal fermentation, nutrient digestibility and methane (CH4) emissions. The heifers were blocked in five groups on the basis of BW and used in five 28-day periods. Dietary treatments included (1) Control and three strains of Propionibacterium (2) P169, (3) P5, and (4) P54. Strains were administered directly into the rumen at 5×109 CFU with 10 g of a maltodextrin carrier in a gel capsule; Control heifers received carrier only. All heifers were fed the basal diet (10 : 90 forage to concentrate, dry matter basis). Rumen contents were collected on days 15 and 18, ruminal pH was measured continuously between days 15 and 22, enteric CH4 emissions were measured between days 19 and 22 and diet digestibility was measured from days 25 to 28. Mean ruminal pH was 5.91 and was not affected by treatments. Similarly, duration of time that pH<5.8 and 5.6 was not affected by treatment. Likewise, total and major volatile fatty acid profiles were similar among all treatments. No effects were observed on dry matter intake and total tract digestibility of nutrients. Total enteric CH4 production (g/day) was not affected by Propionibacterium strains and averaged 139 g/day. Similarly, mean CH4 yield (g CH4/kg of dry matter intake) was similar for all the treatments. The relative abundance of total Propionibacteria in the rumen increased with administration of DFM and were greater 3 h post-dosing relative to Control, but returned to baseline levels before feeding. Populations of Propionibacterium P169 were higher at 3 and 9 h as compared with the levels at 0 h. In conclusion, moderate persistency of the inoculated strains within the ruminal microbiome and pre-existing high propionate production due to elevated levels of starch fermentation might have reduced the efficacy of Propionibacterium strains to increase molar proportion of propionate and subsequently reduce CH4 emissions.

Effect of Propionibacterium spp. on ruminal fermentation, nutrient digestibility, and methane emissions in beef heifers fed a high-forage diet.

The objective of this study was to test the efficacy of different Propionibacterium strains in mitigating methane (CH4) emissions in beef heifers fed a high-forage diet. Twenty ruminally cannulated beef heifers were used in a randomized block design with 28-d periods. Treatments included 1) Control, 2) Propionibacterium acidipropionici strain P169, 3) Propionibacterium acidipropionici strain P5, and 4) Propionibacterium jensenii strain P54. Strains (5 × 10(9) CFU) were administered daily directly into the rumen in 10 g of a maltodextrin carrier in a gel capsule. Control heifers received the carrier only. All heifers were fed a basal diet (70:30 forage to concentrate, DM basis) based on barley silage and corn grain. No treatment effects were observed for overall DMI (P = 0.78) or DMI in chambers (P = 0.29). Dry matter intake was 12 to 29% less in the chambers, with intake depression numerically lower in heifers receiving Propionibacterium than Control. Mean ruminal pH averaged 6.47 and was not affected by treatments (P = 0.34). Likewise, no treatment differences were observed for ruminal concentrations of total VFA (P = 0.24) and ammonia-N (P = 0.49) or for molar proportion of individual VFA. Total daily enteric CH4 production was not affected by Propionibacterium strains as compared to Control and averaged 178 g/d (P = 0.69). However, enteric CH4 emission intensity (g CH4/kg of DMI) was reduced by 12, 8, and 13% with P169, P5, and P54 as compared to Control, respectively (P = 0.03). No treatment effects were observed for total tract digestibility of nutrients. Likewise, total universal bacterial (P = 0.22) and methanogen (P = 0.64) counts were similar among treatments. However, the relative abundance of total Propionibacteria tended to increase with inoculation as compared to Control (P = 0.06). The relative abundance of Propionibacterium P169 tended to be greater at 3 h postdosing, but returned to pretreatment (0 h) levels within 9 h, suggesting it failed to persist at detectable levels in the rumen. In conclusion, Propionibacterium spp. did not reduce total enteric CH4 production, possibly due to their inability to persist and integrate into the ruminal microbial community. However, CH4 emission intensity was reduced with Propionibacterium strains, a response attributed to the numerically greater DMI of heifers receiving Propionibacterium.

Cattle methane emission and pasture carbon dioxide balance of a grazed grassland.

Grasslands constitute a major land use globally and are a potential sink of atmospheric carbon dioxide (CO). They are also an important habitat for wildlife and a source of feed that supports ruminant livestock production. However, the presence of ruminants grazing these grasslands is also a source of methane (CH) that contributes to buildup of greenhouse gases in the atmosphere. Our study measured enteric CH from 40 confined heifers in 1-ha paddocks using a dispersion model and CO exchange from an adjacent grassland site using a micrometeorological technique. The study was conducted at a mixed prairie grassland located in southern Alberta, Canada. The mean (standard error) CH emission was 189 (± 6) g animal d over four campaigns (over a 3-yr period). The daily averaged CO exchange from the grassland peaked at +2.2 g m h (sink) in early July and declined to negative values (source) in mid-August. Annually, the grazed grassland was either a net sink for carbon (C) at +40 kg C ha or a small source at -7 kg C ha depending on a cattle stocking density of 0.1 or 0.2 animals ha, respectively. However, in basing the exchange on CO equivalence (CO), both stocking densities resulted in the grazed grassland being a source of greenhouse gas of -9 or -338 kg CO ha y. This study illustrates the need to consider the cattle CH emissions and the stocking density when evaluating the environmental sustainability of grazed grasslands.